US2007966A

US2007966A - Steam separator

Info

Publication number: US2007966A
Application number: US658905A
Authority: US
Inventors: Fletcher James
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1933-02-28
Filing date: 1933-02-28
Publication date: 1935-07-16
Anticipated expiration: 1952-07-16

Description

July 16, 1935; J FLETCHER 2,007,966

STEAM SEPARATOR Filed Feb. 28, 1933 Fi T 1 I 15 14 15 lN\ IEN'l 'OR James Heicher- @ztem ATTORNEY waited duly lib 113% learnt STEAM SEPARA'K'QE Application February 2%, 1933, Serial No. 658,9il5

lit) Claims.

The present invention relates to the construction and mode of operation of fluid separators and particularly to separators especially adapted for use in a boiler steam and water drum for the ii removal therein of moisture and other impurities carried by the steam.

The general object of my invention is the provision of a steam separator which is characterized by its compactness, effectiveness, and simplicity of construction. A further and more specific object is the provision of a steam boiler drum separator which is characterized by its eifectiveness in operation at high steaming rates and varying drum water levels, and by its capacity for permitting maximum accessibility to the interior of the drum. A further object is the provision of simple and efiective steam washing means in conjunction with the separating provisions.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better under standing of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawing and descriptive matter in which I have illustrated and described a preferred embodiment of my invention.

Of the drawing:

Fig. 1 is a fragmentary conventional illustration of a steam boiler incorporating an embodiment of my invention;

Fig. 2 is an enlarged view of the steam and wa ter drum shown in Fig. l;

3 is an enlarged section on the line iiil of Fig. l is an elevation of one of the spray nozzles;

Fig. 5 is a rear view of the nozzle shown in Fig. 4; and

Fig. 6 is a view similar to Fig. 3, illustrating a modification.

The production of dry steam for the entire operating range of a modern steam boiler has been the objective of many boiler drum separator constructions heretofore proposed. Most of such arrangements have been found objectionable either because of their inherent lack of capacity for effective separation at the higher boiler ratings when maximum variations in water level, foaming and priming tend to occur; because of excessive pressure drop through the separating provisions; or because the drum space occupied by the separating provisions rendered portions of the drum interior inaccessible for inspection and repairs. These objectionable features of prior arrangements are avoided in the drum separator construction hereinafter described.

The invention is illustrated in Fig. 1 as in-= stalled in the steam and water drum it! of a steam boiler of the Babcock a Wilcox cross drum type. Feed water is supplied to the drum as hereinafter described, and descends through downcomer tubes ii connecting the water space of the drum to a bank of steam generating tubes 62. A mixture of steam and water passes from the upper end of the tube bank it through circulators it connected along one side of the drum it, and opening thereto above the normal water level therein. Boiler water usually contains a high concentration of solid material, introduced for the purpose of precipitating scale forming constituents in the water, and other impurities which are carried into the drum in suspension or solution in the steam and water mixture. The fluid mixture enters the drum at a relatively high velocity and the separation which would occur if the drum steam space were unrestricted before passing out through steam outlet or outlets id in the top of the drum would be quite unsatisfactory for modern superheater and turbine requirernents.

The steam separator of my invention comprises a pair of separator sections it extending longitudinally of the drum at opposite sides of the steam outlet iii. The separator sections are spaced apart to form a. central dry steam space it therebetween. Each separator section is pref-= erably formed by a series of closely spaced vertical imperforate corrugated plates ill arranged side-by-side longitudinally of the drum, and forming a series of narrow sinuous channels it] extending transversely of the drum, as shown in Fig. 3 and as described and claimed in the copending application of James C. Hobbs, Serial No. 646,453, filed December 9, 1932. The separator sections are arranged with the ends of the channels adjacent the drum center line opening to the dry steam space it, and their opposite ends in communication with the interior of the drum. The plates iii are continuously curved to form a series of shallow corrugations ill having reversely curved connecting portions ii and preferably slightly nested to provide a turbulent flow of the fluid mixture therethrough only sumcient to bring substantially all portions of the flowing mixture into contact with the smooth moisture collecting surfaces formed by the plates during the passage of the mixture therebetween. The plates i'i are held in the desired spaced relation, as shown in 5|, as shown in Fig. 6.

' through the channels l8.

The lower ends of the channels l8 open to a collecting space formed by a solid drain plate I9 extending between the lower outer corners of the separator sections, and the sections are preferably arranged with an opposite inclination or upwardly diverging formation, as shown, to compensate for the inertia of the moisture particles collecting in each corrugated portion of the plates, providing a gravity flow of the separated moisture with little or no intermingling of the moisture collecting on adjacent corrugated portions. This construction and arrangement helps to minimize the amount of separated moisture swept up by subsequent portions of the flowing mixture. The separated moisture collecting on the plate I9 is removed through longitudinally spaced drain pipes 20, the lower ends of which are'sealed as hereinafter described.

Short circuiting of the separator channels l8 through the moisture collecting space is avoided by the arrangement of an inverted V-shaped sealing plate 22 between the adjacent lower corners of the sections. The plate 22 and the inner ends of the separator sections are supported by suitably supported angle bars 23. The separator sections are supported from the upper portion of the drum wall through angle bars 26, plate members 21, and bolts 28. As shown in Fig. 2, corresponding end portions of the plates l9 and 21 are extended to partially close the inlet ends of the channels l8, while the outlet ends of the channels are unrestricted, to reduce the discharge velocity of the mixture to a point at which the inertia of the fluid is insuflicient to overcome the force of adhesion between the separated moisture and moisture collecting surfaces.

Equalization of flow through the two separator sections and distribution of the entering steam relative to a water spray hereinafter described is obtained by the arrangement of a plate 29 formed with small perforations 30 so as to enclose the separator sections. Corresponding perforated portions of the plate 29 are spaced from the inlet ends of the channels l8 to provide an entrance space for each section in which the fluid velocity is reduced and moisture may separate. v

1 To further reduce the amount of solid material carried out by the steam, the mixture of steam and water is advantageously washed with relatively pure feed water prior to its passage The provisions for this purpose comprise feed water supply pipes 32 extending through the lower wall of the drum and diverging upwardly to the corresponding separator sections. The discharge end of each pipe extends through a corresponding portion of the plate 29 and terminates adjacent thereto in a semi-circumferential discharge slot 33, alongside which is arranged a fan shaped plate 34 as shown in Figs. 4 and 5 to provide a fish-tail spread of the discharged water. By this arrangement, the mixture entering through the plate perforations 30 must pass through a water curtain before entering either row of channels l8. The descending water reduces the velocity of the mi ture and acts as a collector for the moisture and solid particles in the mixture, loading each particle until its inertia either causes it to drop out of the stream before entering the channels or brings it into contact withthe moisture collecting surfaces. The mixture entering the channels will have its previously impure moisture content replaced by'relatively pure feed water, which is removed therefrom during its passage through the separator section.

A perforated plate 24 is arranged along and slightly spaced from the discharge end of each bafiie section, as shown in Fig. 2, to promote a uniform steam distribution through the channels of the corresponding section by lessening the effect of the outlet M on the adjacent portions of the baffle sections. This location of the plates 24 is advantageous as the separator drainage system will not be affected by any consequent increase in pressure at the outlet side of the bafiie section. Moreover, the steam having been washed and the moisture separated prior to this point, the plate perforations tend to remain open.

Special drain provisions for the separated moisture are shown in Fig. 2 and comprise a U- shaped. lower end for the drain pipe 20 formed by a horizontal pipe 4| and an enlarged vertical pipe d2, opening at its upper end above the water level in the drum. An overflow pipe 43 is positioned within and spaced from the walls of the pipe 42. The lower end of the pipe 43 opens adjacent the bottom of the drum and its upper end below the upper end of the pipe 42, but above the water level in the drum. In normal operation the water draining from the separator overflows into the pipe 43 from the pipe 42 and then to the pool in the drum. The normal level of water in the pipe 42 provides an effective seal against the entrance of steam into the pipe 20. In the event the pressure differential across the separator increases due to solid deposits therein or any other abnormal condition, only the water forming the seal can be forced up into the separator by the steam pressure. The arrangement of the pipes 42 and. 43 prevents the'return of any of the water in the drum pool to the separator under these conditions.

The separator construction described is highly compact and occupies only a relatively small portion of the drum interior. All the parts can be introduced through the drum access opening 40 and assembled in the interior of the drum. The compact arrangement of the separator in the top of the drum permits easy access to the portions of the drum into which the circulators l3 and downcomers H are connected for inspection or replacement of those parts as well as caulking of .the drum buttstraps. It has been found that the effectiveness of the separating action is not changed by normal variations in drum water level or by substantial increase in the discharge velocity from the circulators l3.

While in accordance with the provisions of the statutes I have illustrated and described herein the best form of m invention now known to me, those skilled in t art will understand that changes may be made in the form of theapparatus disclosed without departing from the spirit of the invention covered by my claims, that certain features of my invention may sometimes be used to advantage without a corresponding use of other features, and that the use of my invention is not limited to any particular type of boiler.

acumen lclaim:

1. In a steam and water drum having steam and water circulators connected thereto along one side thereof and above the normal water level therein, downcomers connected to the bottom thereof, and a steam outlet in its upper side, a steam and water separator extending longitudinally of and in the upper portion of said drum and comprising a pair of oppositely inclined separator sections at opposite sides of said drum outlet with a dry steam space therebetween, each section being formed by a plurality of side-byside imperforate corrugated plates arranged to form narrow sinuous open ended channels therebetween extending transversely of said drum and with a series of corrugations extending transversely of the general direction of flow in said channels, means closing the space between each section and the upper portion of said drum, a moisture collecting chamber receiving separated moisture from the bottoms of said sections, and a drain pipe connected to said chamber.

2. In a drum having steam and water connections thereto, and a steam outlet in its upper side, a steam and water separator extending longitudinally of and in the upper portion of said drum and comprising a pair of oppositely inclined separator sections at opposite sides of said drum outlet with a dry steam space therebetween, each section being formed by a plurality of side-byside plates arranged to form narrow channels therebetween extending transversely of said drum, and a perforated plate arranged along the steam inlet end of the channels in each of said separator sections.

3. In a drum having steam and water connections thereto, and a steam outlet in its upper side, a steam and water separator in the upper portion ofsaid drum, a chamber receiving moisture separated in said separator, a 'U-shaped drain pipe opening into said chamber and having its other end opening above the water level in said drum, and an overflow connection opening to the open end of said U-shaped tube above the water level in said drum.

4. In a drum having a steam connection thereto above the normal water level therein, and a steam outlet in its upper side, a steam and water separator in the upper portion of said drum and comprising a pair of separator sections at opposite sides of said drum outlet with a dry steam space therebetween, each section being formed by a plurality of side-by-side plates arranged to form narrow open ended channels therebetween, a perforated cover plate spaced from and enclosing the inlet ends of the channels of both sections, and means for establishing a water curtain between said cover plate and the inlet end of the channels of each section.

5. In a steam and water drum having steam and water circulators connected thereto along one side thereof and above the normal water level therein, downcomers connected to the bottom thereof, and a steam outlet in its upper side, a steam and water separator extending longitudinally of and in the upper portion of said drum and comprising a pair of separator sections at opposite sides of said drum outlet with a dry steam space therebetween, each section being formed by a plurality of side-by-side plates arranged to form narrow sinuous open ended channels therebetween extending transversely of said drum and with a series of corrugations extending transversely of the general direction of flow in said channels, a perforated cover plate spaced from and enclosing the inlet ends of the channels of both sections, and means for establishing a water curtain between said cover plate and the inlet ends of the channels of each section.

6. Steam treating apparatus comprising a casing having a steam outlet in its upper side, a steam and water separator in the upper portion of said casing including a pair of oppositely inclined separator sections arranged at opposite sides of said steam outlet to provide a dry steam space therebetween, each separator section comprising a series of corrugated plates having their corrugations extending substantially transverse- 1y of the general direction of steam flow relative thereto, means for holding said plates in sideby-side relation to form narrow undulating channels therebetween closed at their upper ends, plate means extending between the outer lower corners of said separator sections and arranged to form a moisture collecting chamber directly communicating with the lower ends of said channels throughout a substantial portion of their length, plate means for supporting said separator sections at the lower inner corners thereof and separating said moisture collecting chamber from said dry steam space, and means for draining the collected moisture from said moisture collecting chamber.

'7. Steam treating apparatus comprising 2. casing having a steam outlet in its upper side, a steam and water separator in the upper portion of said casing including a pair of oppositely in-= clined separator sections arranged at opposite sides of said steam outlet to provide a dry steam space therebetween, each separator section comprising a series of corrugated plates having their corrugations extending substantially transversely of the general direction of steam flow relative thereto, means for holding said plates in side-byside relation to form narrow undulating channels therebetween closed at their upper ends, plate means extending between the outer lower corners of said separator sections and arranged to form a moisture collecting chamber directly communieating with the lower ends of said channels throughout a substantial portion of their length, plate means for supporting said separator sections at the lower inner corners thereof and separating said moisture collecting chamber from said dry steam space, means for draining the collected moisture from said moisture collecting chamber, and means for restricting the effective flow area at the outer side of said channels.

8. Steam treating apparatus comprising a casing having a steam outlet in its upper side, a steam and water separator in the upper portion of said casing above the normal level of a water pool therein and including a pair of oppositely inclined separator sections arranged at opposite sides of said steam outlet to provide a dry steam space therebetween, each separator section com-- prising a series of corrugated plates having their corrugations extending substantially transversely of the general direction of steam fiow relative thereto, means for holding said plates in side-byside relation to form narrow undulating channels therebetween closed at their upper ends, plate means extending between the outer lower corners of said separator sections and arranged to form a moisture collecting chamber directly communicating with the lower ends of said channels throughout a substantial portion of their length, means for separating said moisture collecting chamber from said dry steam space, a water sealed drain pipe for draining the collected moisture from said moisture collecting chamber, and a perforated plate arranged along the inner side of each of said separator sections to provide a substantially uniform steam flow through the channels thereof.

9. Steam treating apparatus comprising a casing having a dry steam outlet in its upper side, a steam and water separator in the upper portion of said casing above the normal level of a Water pool therein and including a pair of separator sections arranged at opposite sides of said steam outlet to provide a dry steam space therebetween, means arranged to form a moisture collecting chamber communicating with said separator sections, means for separating said moisture collecting chamber from said dry steam space, means for draining said moisture collecting chamber comprising a U-shaped drain pipe connected at one end to said chamber and having its opposite end opening to said casing above the normal level of the water pool therein, and means for conveying the overflow from said drain pipe to said water pool substantially without contact by the steam passing through said casing.

10. Steam treating apparatus comprising a casing having a steam outlet in its upper side, a

aooaooo steam and. water separator in the upper portion of said casing including a pair of oppositely inclined separator sections arranged at opposite sides of said steam outlet to provide a dry steam space therebetween, each separator section comprising a series of corrugated plates having their corrugations extending substantially transversely of the general direction 'of steam flow relative thereto, means for holding said plates in side-byside relation to form narrow undulating channels therebetween closed at their upper ends, plate means extending between the outer lower corners of said separator sections and arranged to form a moisture collecting chamber directly communicating with the lower ends of said channels throughout a substantial portion of their length, plate means for supporting said separator sections at the lower inner corners thereof and separating said moisture collecting chamber from said dry steam space, means for draining the collected moisture from said moisture collecting chamber, and means in said casing for spraying water into the steam prior to its passage through the channels of said separator sections.

JAMES FLETCHER.